//         Elem typeOff
//     }
//
//     type ArrayType struct {
//         Tag  itag // arrayType
//         Len  uint64
//         Elem typeOff
//     }
//
//     type ChanType struct {
//         Tag  itag   // chanType
//         Dir  uint64 // 1 RecvOnly; 2 SendOnly; 3 SendRecv
//         Elem typeOff
//     }
//
//     type MapType struct {
//         Tag  itag // mapType
//         Key  typeOff

	{"SliceType", `@[]T`},
	{"DotsType", `@...T`},
	{"StructType", `@struct{}`},
	{"InterfaceType", `@interface{}`},
	{"FuncType", `func@()`},
	{"MapType", `@map[T]T`},

	{"ChanType", `@chan T`},
	{"ChanType", `@chan<- T`},
	{"ChanType", `@<-chan T`},
}

var fields = []test{
	{"Field", `@T`},
	{"Field", `@(T)`},
	{"Field", `@x T`},
	{"Field", `@x *(T)`},
	{"Field", `@x, y, z T`},

		// types
		// case *ArrayType:
		// case *SliceType:
		// case *DotsType:
		// case *StructType:
		// case *Field:
		// case *InterfaceType:
		// case *FuncType:
		// case *MapType:
		// case *ChanType:

		// statements
		// case *EmptyStmt:
		// case *LabeledStmt:
		// case *BlockStmt:
		// case *ExprStmt:
		case *SendStmt:
			m = n.Chan
		// case *DeclStmt:
		case *AssignStmt:
			m = n.Lhs

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"io/fs"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"sync"
	"testing"
)

var typeNames = []string{
	"uncommonType",
	"arrayType",
	"chanType",
	"funcType",
	"interfaceType",
	"ptrType",
	"sliceType",
	"structType",
}

type visitor struct {
	m map[string]map[string]bool
}

func newVisitor() visitor {
	v := visitor{}

	case *ast.BlockStmt:
		return 1 << nBlockStmt
	case *ast.BranchStmt:
		return 1 << nBranchStmt
	case *ast.CallExpr:
		return 1 << nCallExpr
	case *ast.CaseClause:
		return 1 << nCaseClause
	case *ast.ChanType:
		return 1 << nChanType
	case *ast.CommClause:
		return 1 << nCommClause
	case *ast.Comment:
		return 1 << nComment
	case *ast.CommentGroup:
		return 1 << nCommentGroup
	case *ast.CompositeLit:

		writeFieldList(buf, x.Methods.List, "; ", true)
		buf.WriteByte('}')

	case *ast.MapType:
		buf.WriteString("map[")
		WriteExpr(buf, x.Key)
		buf.WriteByte(']')
		WriteExpr(buf, x.Value)

	case *ast.ChanType:
		var s string
		switch x.Dir {
		case ast.SEND:
			s = "chan<- "
		case ast.RECV:
			s = "<-chan "
		default:
			s = "chan "
		}
		buf.WriteString(s)
		WriteExpr(buf, x.Value)
	}

			Walk(v, n.Params)
		}
		if n.Results != nil {
			Walk(v, n.Results)
		}

	case *InterfaceType:
		Walk(v, n.Methods)

	case *MapType:
		Walk(v, n.Key)
		Walk(v, n.Value)

	case *ChanType:
		Walk(v, n.Value)

	// Statements
	case *BadStmt:
		// nothing to do

	case *DeclStmt:
		Walk(v, n.Decl)

	case *EmptyStmt:
		// nothing to do

	case *LabeledStmt:

	case *ast.ArrayType:
		if t.Len == nil {
			return fmt.Sprintf("types.NewSlice(%s)", i.subtype(t.Elt))
		}
		return fmt.Sprintf("types.NewArray(%s, %d)", i.subtype(t.Elt), intconst(t.Len))
	case *ast.ChanType:
		dir := "types.Cboth"
		switch t.Dir {
		case ast.SEND:
			dir = "types.Csend"
		case ast.RECV:
			dir = "types.Crecv"
		}
		return fmt.Sprintf("types.NewChan(%s, %s)", i.subtype(t.Value), dir)

	case *InterfaceType:
		w.fieldList(n.MethodList)

	case *FuncType:
		w.fieldList(n.ParamList)
		w.fieldList(n.ResultList)

	case *MapType:
		w.node(n.Key)
		w.node(n.Value)

	case *ChanType:
		w.node(n.Elem)

	// statements
	case *EmptyStmt: // nothing to do

	case *LabeledStmt:
		w.node(n.Label)
		w.node(n.Stmt)

	case *BlockStmt:
		w.stmtList(n.List)

		ParamList  []*Field
		ResultList []*Field
		expr
	}

	// map[Key]Value
	MapType struct {
		Key, Value Expr
		expr
	}

	//   chan Elem
	// <-chan Elem
	// chan<- Elem
	ChanType struct {
		Dir  ChanDir // 0 means no direction
		Elem Expr
		expr
	}
)

type expr struct {
	node
	typeAndValue // After typechecking, contains the results of typechecking this expression.
}